Pollutants are compounds which are dangerous to the environment.
They can also be harmful to humans in the long-term range. They come from mineral and fossil sources or are produced by humans themselves.
Many pollutants have a poisonous effect on the body. Carbon monoxide is an example of a substance which is damaging to humans. This compound is taken up in the body instead of oxygen. That makes the body suffocate and in severe cases may lead to death.
Some pollutants became dangerous by reaction with other naturally occurring compounds. The oxides of nitrogen and sulphur are released from impurities in fossil fuels when they are burnt. They react with water vapour in the atmosphere to become acid rain. Acid rain damages buildings and makes lakes unable to support marine life, which causes fish and water plants to die.
- Agency for Toxic Substances and Disease Registry
- Miriam-Webster definition of pollutes[permanent dead link]